16A TAC Report

by Dana Balser last modified Jan 31, 2017

Summary

A total of 324 proposals were submitted to NRAO's North American facilities for semester 16A.  This includes the Robert C. Byrd Green Bank Telescope (GBT), the Very Long Baseline Array (VLBA)/High Sensitivity Array (HSA), and the Karl G. Jansky Very Large Array (VLA).  Proposals are reviewed on a competitive basis with a panel review system (see Proposal Review System).  Below are the statistics by proposal count and hours.  The oversubscription is the ratio of the number of submitted proposals to the number of approved proposals.  The pressure is the ratio of the requested time to the available time in hours.  Here we only include proposals submitted for the 16A semester that have been reviewed by the NRAO TAC.  For the VLA and GBT we count HSA and GMVA proposal hours that request them as a VLBI station.

 

Statistics by Proposal Count
ProposalsGBTVLBAVLANRAO
Submitted 49 41 234 324
Approved 16 21 99 136
Filler 11 10 71 92
Rejected 22 10 64 96
Oversubscription 3.1 2.0 2.4 2.4

 

Statistics by Proposal Hours
ProposalsGBTVLBAVLA (B)VLA (C)VLA (BnC)VLA (Total)NRAO
Requested 4729 1697 3746 3452 305 7503 13929
Available 1747 1159 1443 1384 310 3137 6043
Approved 1486 880 606 882 125 1613 3979
Filler 9321 244 1318 1206 180 2704 12269
Rejected 1227 573 1822 1364 0 3186 4986
Pressure 2.7 1.5 2.6 2.5 1.0 2.4 2.3

 

For the 16A semester, the NRAO had agreements with the Hubble Space Telescope (HST), the Swift Gamma-Ray Burst Mission, and the Chandra X-ray Observatory to submit joint proposals whereby the NRAO TAC could allocate time on these external facilities (see the 16A Call for Proposals).   The table below summarizes the results for 16A.

 

Joint External Proposals

HST (Orbits)

Swift (ks)Chandra (ks)
Available 30 300 120
Requested 7 50.5 137
Approved 0 35.5 0

 

Telescope Pressure Plots

Pressure plots show the total hours of allocated time as a function of LST (or GST for the VLBA) for each telescope.   Also shown are how the hours are divided with respect to weather conditions and observing priority.  Click on the plot to view the source file.

 

GBT

The GBT has three weather categories: poor (below 8 GHz), good (between 8-18 GHz and 26.5-50 GHz), and excellent (18-26.5 GHz and above 50 GHz).  The first three figures below show the pressure plots for each these weather categories.  The last figure includes all weather categories.  The grey horizontal line shows the total available hours.  The letters A, B, and C correspond to the priorities assigned by the TAC where A and B are approved time and C is filler time.  Carryover is time allocated by a TAC from a previous semester that is being executed in the 16A semester.

 

 GBT Pressure Plot for Poor Weather

 GBT Pressure Plot 16A (Good)

 GBT Pressure Plot 16A (Excellent)

 GBT Pressure Plot 16A (Total)


VLBA

The VLBA has two weather categories: high frequency (above 12 GHz, light shading) and low frequency (below 12 GHz, dark shading).  The two black lines are 50% (solid) and 70% (dashed) of the time available, respectively. The green dots and line are based on teh mean of actual observing hours in semesters 12A, 13A, and 14A. The letters A, B, C, and N correspond to the priorities assigned by the TAC where A and B are approved time, C is filler time, and N is rejected time.  Pre-committed (carryover) time is time allocated by a TAC from a previous semester that is being executed in the 16A semester.

 

 VLBA Pressure Plot 16A

 


VLA

The VLA has two weather categories: high frequency (above 12 GHz, light shading) and low frequency (below 12 GHz, dark shading). The three figures below show the pressure for the B, C, and CnB configurations.  The black lines indicate the total time available for science (solid), the time available for K-band and higher and higher frequencies (dashed), and the time available for Q-band (dotted).  The letters A, B, C, and N correspond to the priorities assigned by the TAC where A and B are approved time, C is filler time, and N is rejected time.

 

 VLA Pressure Plot 16A (B)

 VLA Pressure Plot 16A (C)

 VLA Pressure Plot 16A (BnC)

 

 

Observation Preparation

 

GBT

Please use the GBT Dynamic Scheduling System (DSS) to enable observing sessions, select observers for your project, and enter your blackout dates. The DSS Home Page has additional information about the DSS.  See GBT Observing for information about how to prepare for your observations.

Please note that the DSS uses the average Right Ascension (RA) and Declination (Dec) of all sources within a session.  The average RA and Dec will be used to determine when the session can be scheduled.  You will need to carefully check the RA and Dec, along with the minimum and maximum session lengths, to make sure that these values are satisfactory and will allow all your sources to be observed before enabling the session.

 

VLBA

In semester 16A, Galactic parallax projects require much of the VLBA  time in inner Galaxy GSTs (~2100 - 0400 GST) in the parallax "season",  which is approximately ±3 weeks centered on the equinoxes. Twenty-four hour blocks are very difficult to schedule during that time. If at all possible, dynamic blocks should avoid those GSTs during that time of the year.

Unless otherwise stated in the TAC comments, proposals approved for priority A time will be eligible for scheduling in semesters 16A and 16B, and proposals approved for priority B or C time will be eligible for scheduling only during semester 16A.

IMPORTANT: Those allocated dynamic time should begin their .key file preparation about two weeks before 2016 February 1, the start of semester 16A.

Any approved time tabulated above may be divided into multiple scheduling  blocks as appropriate, considering the scheduling priority, observing frequency, GST range suitable for the target(s), and GST pressure. For advice on preparing your scheduling blocks, please consult the VLBA Observing Guide.

 

VLA

In semester 16A daytime maintenance activities peak at about 04 hours LST, for C configuration and 10 hours LST for B configuration, so proposal pressure is highest there. Proposals approved for priority A, B or C time become ineligible when the associated configuration ends, unless explicitly stated otherwise in the Comments from the TAC. Those allocated dynamic time should begin their scheduling block preparation about two weeks before the planned start of the configuration (see Configuration Plans).

Any approved time may be divided into multiple scheduling blocks as appropriate, considering the scheduling priority, observing frequency, LST range suitable for the target(s), and LST pressure. For advice, please consult the VLA Observing Guide.

Unless stated otherwise, any time allocated is only for the identified proposal, and no modification in the project should be made without obtaining permission from NRAO scheduling staff.  To seek permission, submit a ticket to the Proposal Review department of the NRAO Helpdesk.